1. Field of the Invention
This invention is related to an improved method of aligning a nozzle plate with a mask.
2. Description of the Prior Art
Ink-jet printers generally fall into two categories, i.e. the bubble type ink-jet printers and the piezoelectric ink-jet printers. For piezoelectric ink-jet printers, what we concern most is related to the method of how to align the nozzle plate with a film in the manufacture of print heads in an effective way.
In the structure of piezoelectric ink-jet printers, the ink cabin is made by first pressing seven layers of high molecular material to form a spacer and then processing the film with mask etching method. The nozzle plate is formed with a plurality of nozzles and the mask has corresponding layouts of ink cabins. As the mask is etched, each of the nozzles must be in alignment with an ink cabin so that the ink cabin layout of the mask must be accurately aligned with corresponding nozzles of the nozzle plate.
In order to make it easier for alignment, the nozzle plate and the mask must be provided with nozzle positioning marks and layout positioning marks respectively, wherein every four of the nozzle positioning marks and every four of the layout positioning marks define a nozzle and an ink cabin respectively. Each of the nozzle positioning marks and layout positioning marks is represented by a sign +. In other words, each nozzle positioning mark is defined between four marks + on the nozzle plate, and each ink cabin is also defined between four marks + on the mask. It is only required for the operator to align the mark + of the nozzle plate with the mark + of the mask. Of course, it is only necessary to align two marks +. However, it is recommended to align the marks + which have the largest distance therebetween, usually the marks + at two diagonal corners.
Referring to FIGS. 1 and 2, the nozzle plate 11 is formed with a plurality of nozzles 111 each having an ink cabin 17. The ink cabin 17 is produced by first aligning the layout positioning marks 132 with the nozzle positioning marks 112 and then etching the area 113 of the film 12 on the nozzle plate 111.
As a result, each of the nozzles of the nozzle plate 11 is formed with an ink cabin 17. As shown, the nozzle positioning mark 112 is arranged under the film 12 so that it is necessary to see through the film 12 when aligning the mask with the nozzle plate.
Referring to FIG. 3, the conventional film 12 is made by pressing three layers of high molecular material which light can pass through, so that there will be no difficulties in aligning the mask with the nozzle plate. As shown in FIG. 3, the mask 13 is moved by a distance d in order to align the layout positioning mark 132 with the nozzle positioning mark 112 of the nozzle plate 11.
However, when required to increase the thickness of the film on the nozzle plate to a structure with seven layers, it will be very difficult to locate the nozzle positioning marks under the film.
Referring to FIG. 4, it is very difficult to see the nozzle positioning marks 112 of the nozzle plate 11 through a seven-layer film 12 thereby making it difficult to align the layout positioning marks 132 of the mask 13 with the nozzle positioning marks 112 thus seriously influencing the working efficiency.
Therefore, it is an object of the present invention to provide an improved method of a nozzle plate with a mask which can obviate and mitigate the above-mentioned drawbacks.